The ‘S’ in Canon’s EF-S Lens Mount Stands for “Small Image Circle”

If you’re a crop sensor Canon shooter, you may have learned in the past that the ‘S’ in EF-S stands for “Short-Back Focus”. Well, that’s not true anymore. The lens mount was originally for lenses with rear elements closer to the sensor plane than in EF lenses, but there are recent EF-S lenses that eschew the short back design. The moniker now stands for “Small Image Circle”, as evidenced by this technical report.

(via The Digital Picture)

Image credit: Canon EF-S 10-22 f/3.5-4.5 by Pixeloflight

  •!/thelonelylights Adam Cross

    love the 10-22 =]

  • The_photographer_Tom

    I thought that the “S” didn’t actually mean anything apart from the fact fact I couldn’t use it on a full frame camera.

  • 9inchnail

    So from now on I have no idea whether I can use a lens with a full frame body or not without doing some research first. Great :-/

  • RioRyan

    How do you figure? The same rules still apply. The EF-S is APS-C only.

  • 9inchnail

    “there are recent EF-S lenses that eschew the short back design”

    The way I read it, you can use these for full frame bodies since the lenses don’t get near the sensor anymore. May not be the most sensible choice but you should be able to use them, right?

  • Patti Gould

    Same rules still apply. EF-S lenses are still not compatible with EF ONLY camera bodies.